Difunctional Fatty Soap Based Greases

ABSTRACT

Monohydroxy fatty acids are cyanoethylated and the resulting cyanoethoxy derivative is treated with the desired alkali, alkaline earth metal or other metallic base to form a soap which is dispersed in a petroleum oil base or a synthetic base oil of the diester type to form a grease.

United States Patent [191 Kenney et al.

[ 1 Feb. 4, 1975 [73] Assignee: The United States of America as represented by the Secretary of Agriculture, Washington, DC.

[22] Filed: July 25, 1972 [21] Appl.No.: 275,011

[52] US. Cl. 260/404, 252/33.6 [51] Int. Cl C08h 17/36 [58] Field of Search 260/404 [56] References Cited OTHER PUBLICATIONS Maerker et al., Journ. Amer. Oil Chem. Soc. 45(2),

Primary Examiner-Lewis Gotts Assistant ExaminerEthel G. Love Attorney, Agent, or FirmM. Howard Silverstein; Max D. Hensley; William E. Scott [57] ABSTRACT Monohydroxy fatty acids are cyanoethylated and the resulting cyanoethoxy derivative is treated with the desired alkali, alkaline earth metal or other metallic base to form a soap which is dispersed in a petroleum oil base or a synthetic base oil of the diester type to form a grease.

14 Claims, N0 Drawings DIFUNCTIONAL FATTY SOAP BASED GREASES A non-exclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all purposes of the US. Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

This invention relates to soaps of cyanoethylated hydroxy substituted fatty acids and more specifically to the use of alkali, alkaline earth metal and other metallic soaps of such fatty acids to make multipurpose greases.

Small amounts of certain chemical compounds are commonly added to lubricants to improve their physical properties. Typical additives include oxidation or corrosion inhibitors, anti-wear improvers, water repellents, and dyes. One problem in formulated greases containing additives is that in storage and in use these additives tend to migrate in the base oil and in extreme cases cause the grease to separate. Another problem is the frequent tendency for two additives to be incompatible which complicates the task of formulation. Most lubricants are blended with an additive to improve their anti-wear function. The soaps of this invention improve the wear properties of the base oils with which they are mixed without use of additives. Another important feature of this invention is that the two functional groups responsible for anti-wear and grease forming properties are incorporated into the same molecule. Consequently, it is impossible for migration or incompatibility to occur in greases made from these soaps.

In addition to being grease formers, the difunctional fatty derivatives of this invention impart anti-wear properties to the resulting greases. They have the added feature of forming two classes of greases from two types of base oils, one based on petroleum oil and the other on diester type oils. The petroleum oils have the advantage of good lubricity and low cost while the diester type oils impart wide temperature range performance characteristics.

An object of this invention is to prepare stable greases by dispersing the difunctional soaps of this invention in petroleum oil of lubricating viscosity.

Another object is to prepare stable greases by dispersing the difunctional soaps of this invention in synthetic base oils of the diester type.

Still another object is to provide difunctional fatty soaps and derivatives that impart anti-wear properties to greases.

In general, according to this invention the above objects are accomplished by dispersing in petroleum oil or in a synthetic base oil of the diester type, a difunctional fatty soap of the general formula l (CH l 011 0111 -c (CH 'COOR wherein the sum of .r and y is a number from to 20 and R is a metallic ion such as lithium, sodium, calcium, barium, and aluminum. These fatty derivatives are novel compounds in which a 3 carbon side chain having a terminal nitrile group is attached by an ether linkage to the carbon chain of the fatty soap.

Suitable starting materials for the greases formed in this invention are monohydroxy fatty acids either naturally occurring or synthesized by known procedures. The monohydroxy fatty acids are neutralized with a base and the resulting soap mixed with an excess of acrylonitrile. A cosolvent such as water or pyridine should be used. Addition of a catalytic amount of strong base to this mixture causes abstraction of a hydroxyl proton from the fatty acid and formation of the cyanoethoxy derivative. This fatty derivative is recovered from the reaction mixture after acidification. The substituted fatty acids can then be treated with the desired alkali, alkaline earth metal or other metallic base to form the needed soap.

If a petroleum based grease is to be made, the soap of the substituted fatty acid is mixed with the base oil and about 10% by weight of water is added. The mixture is vigorously stirred and heated to 1 10C until the excess water is removed and the grease reaches the desired consistency. The petroleum based grease can also be made by dispersing the fatty acid in the base oil and neutralizing the mixture in situ with an aqueous solution of the appropriate base while stirring and heating at l 10C to remove water until the desired consistency is reached.

A diester based grease is prepared by mixing a preformed fatty soap with the base oil and adding about 30% by weight of water. The mixture is stirred and heated to C until the excess water is removed and then it is allowed to cool with stirring.

The petroleum based greases formed from these cyanoethoxy fatty soaps show considerably better antiwear properties than a standard grease prepared from sodium stearate and in some cases better than two commercially formulated greases (Table l).

The diester based greases formed from the cyanoethoxy fatty soaps showed generally better anti-wear properties than standard sodium stearate diester greases (Table 11).

Suitable monohydroxy fatty acids, for use in the preparation of the cyanoethoxy fatty grease precursor, may vary in chain length from 10-20 carbon atoms with the hydroxy group attached at any point on the chain.

The cationic portion of the soap may be chosen from elements in periodic groups 1, 11, or 111. To demonstrate our invention we have used the five cations, Li", Na", Ca, Ba, and AI most commonly used in commerical soaps. At least one element from each of the first three periodic groups was used.

Suitable oils for the petroleum based greases may be any hydrocarbon oil of lubricating viscosity such as 100 paraffin oil.

The diester based greases can be formulated using any of the commercial diester oils such as di(2- ethylhexyl) sebacate (D.O.S.), di-Z-ethylhexyl azelate (DOA), di-isooctyl azelate (DlOA), and dipropyleneglycol dipelargonate (DPDP).

The amount of cyanoethyl fatty soap used in this invention to form greases is generally less than 30% by weight of formulated grease. The greater the amount of soap the harder the grease. For the purposes of this invention the percentage of soap used in the greases was held constant at 15% when possible so that the wear test results would be comparable.

in making the grease it is important that the mixture is not overheated. Otherwise, the small amount of water necessary for the oil, water, soap complex will be driven off and cause the soap to precipitate.

A cosolvent is needed in the cyanoethylation step to solubilize the fatty soap to obtain a good yield of prod- UCI.

Anti-wear properties were determined using the Shell Four Ball Wear Tester as described by ASTM designation D2266-64T, Federal Test Method Standard No. 7916. Approximately ml of the grease to be tested is placed in the test cup so that the three bottom stationary balls are covered. After positioning the cup on its stnad, in contact with the fourth ball, the grease was heated to 75C, a 40 kg load was placed on the weight tray, and the upper ball was allowed to rotate at 1,200 rpm. for 1 hour. The diameters of the scars worn on the three stationary balls were measured by means of a low power microscope. The results are shown in Table 1 and 11. The hardness of the greases was determined with a Penetrometer as described by ASTM designation D-217-48. A micro-cone was used to check the consistency of small samples. Some of the physical properties of the greases are shown in Tables 1 and 11.

The invention is illustrated by the following examples.

EXAMPLE 1 100 g (0.34 moles) of l2-hydroxystearic acid was treated with benzyltrimethylammonium hydroxide in a 40% methanol solution until a pH of 10.0 was reached. The methanol was driven off with heat, and the soap product was dissolved in 50 ml pyridine and 600 ml acrylonitrile (9.0 moles). To this mixture was added rapidly with stirring, 16 ml of a 40% aqueous solution of Preparation of Petroleum Grease 60 g (0.17 moles) of l2-(2-cyanoethoxy) stearic acid was dissolved in 200 ml acetone and 6.8 gms (0.17 moles) of sodium hydroxide in 200 ml water was added to it with stirring. After stirring for 2 hours the mixture was filtered and the soap dried under vacuum at 1 10C to give 57 g of sodium l2-cyanoethoxy stearate. 1.5 g of sodium l2-cyanoethoxy stearate, 8.5 gms of 100 paraffin oil and 1 ml of water was stirred and heated at 1 10C for about 2 hours and then allowed to cool with stirring. The resulting product was a stable dark yellow grease.

Using the procedure described above the lithium and calcium soap 100 paraffin oil greases were prepared.

Preparation of Diester Grease Sodium 12-(2-cyanoethoxy)-stearate (1.5 g) was mixed with 8.5 gms di-(2-ethylhexyl)-sebacate which contained 3 ml water. After stirring and heating to C for 1.5 hours the mixture was allowed to cool with stirring. The product was a light yellow grease.

Using the procedure described above the lithium and calcium l2-(2-cyanoethoxy) stearate diester greases were prepared.

EXAMPLE 2 37 g (0.12 moles) of 9( l0)-hydroxystearic acid was neutralized with benzyltrimethylammonium hydroxide in a 40% methanol solution to an endpoint of pH 10.0. The solution was concentrated in a rotary vacuum evaporator until dry. Then the soap was mixed with 200 ml (3.0 moles) acrylonitrile containing 9 ml water. To this mixture was added rapidly with stirring 7 ml of a 38.5% aqueous solution of benzyltrimethylammonium hydroxide. After 1 hour of stirring the mixture was diluted with 200 ml water and dilute hydrochloric acid was added until a pH of 2.0 was reached. This mixture was extracted with three 200 ml portions of ether, and the combined extracts were washed with water, dried over sodium sulfate and evaporated to a residue weight of41.5 g. GLC, thin layer chromatography (TLC), and infrared analysis confirmed that the product contained 87% 9(10)-(2-cyanoethoxy) stearic acid and 13% unreacted 9( l0)-hydroxystearic acid.

Preparation of Petroleum Grease To a vigorously stirred mixture of 1.4 g 9(l0)-(2- cyanoethoxy) stearic acid, 8.5 g 100 paraffin oil and 1 ml water at 100C, was added a dilute solution of sodium hydroxide until the acid was neutralized. Stirring and heating to l 10C was continued until the mixture was dehydrated sufficiently to form a grease. Physical properties of this grease are listed in Table 1.

Alternate Procedure for Preparation of Petroleum Grease 3.0 gms (0.0085 moles) of 9(l0)-(2-cyanoethoxy) stearic acid was dissolved in 10 m1 acetone and 0.4 gms (0.0085 moles) of sodium hydroxide in 10 ml water was added to it. The mixture was stirred for 1 hour and then filtered and the soap dried under vacuum at l 10C to give 3.2 g sodium 9(l0)-(2-cyanoethoxy) stearate. 1.5 g. of sodium 9( l0)-(2-cyanoethoxy) stearate, 8.5 g 100 paraffin oil and 1 ml water were stirred and heated at l 10C for about 2 hours or until sufficent water was removed so that the mixture formed a grease when cooled to room temperature.

Using the above procedure the lithium, barium, and aluminum soaps and corresponding 100 paraffin oil based greases were made.

Preparation of Diester Grease 1.5 g of sodium 9( l0)-(2-cyanoethoxy) stearate, 8.5 g di(Z-ethylhexyl) sebacate (D.O.S.) and 3 ml water were stirred and heated to 100C for 1 hour and then allowed to cool with stirring. The resulting product was a light yellow grease. D.O.S. based greases were also made from the lithium, barium, and aluminum 9( l0)- 5 6 (2-cyanoethoxy) stearate soaps by the same procedure. CE N The lithium 9( l)-(2-cyanoethoxy) stearate soap was I used to make the diester greases based on di(2- 2k ethylhexyl) azelate (D.O.A.), di-isooctyl azelate 0 (DIOA) and dipropyleneglycol dipelargonate (DPDP). i

TABLE] CH (CH -C (Cil l COOR lOO PARAFFlN OIL BASED GREASES (7 SL3! g scar wherein the sum of x and y a number from l0 to ra e lumeter Soap Soup Hardness mm andR IS a metallic ion selected from the group consisting of lithium, sodium. calcium. barium. and Lithium 9( l0lcyanoethoxy l5 2 0.600 aluminum 1 5 am e 2. The dlfunctlonal fatty soap of claim I wherein the Lithium l2'cyanoethoxy l5 2 0.710 15 sum f d y i 15 came 3. The difunctional fatty soap of claim 2 wherein R Sodium 9( l0)-cyanoethoxy l5 2 0.523 is lithium,

meme 4. The difunctional fatty soap of claim 2 wherein R Sodium IZ-cyanoethoxy l5 3 0.511 is sodium.

came 20 5. The difunctional fatty soap of claim 2 wherein R Calcium l2-cyanoethoxy I5 I 0.450 is calcium.

came 6. The difunctional fatty soap of claim 2 wherein R Barium 9t 10 )-cyanocthoxy 15 2 0.535 is barium.

came 7. The dit'unctional fatty soap of claim 2 wherein R Aluminum 9( l0)'cyar|oethoxy l0 0 0.690 i5 umsleflme 8. Lithium 9( l0)-cyanoethoxy stearate. Sodium Swarm 15 3 0,890 9. Lithium l2-cyanoethoxy stearate. C I 2 0574 10. Sodium 9( l0)-cyanoethoxy stearate.

" fig jgf' i j g" 11. Sodium l2-cyanoethoxy stearate.

3 O 652 12. Calcium l2-cyanoethoxy stearate. Cmnmerwl sod'um grease l3. Barium 9( l0)-cyanoethoxystearate.

TABLE II DlESTER BASED GREASES NLGI Wear Scar Base Grade Diameter Soap Oil Soap Hardness mm Sodium stearate D.O.S. l5 3 0.985

Lithium 9( l0)-cyanoethoxy stearate D.O.S. l5 1 0.570

Lithium l2-cyanoethoxy stearate D.O.S. l5 0 0.700

Sodium 9( l0)-cyanoethoxy stearate D.O.S. l5 2 0.569

Sodium l2-cyanoethoxy stearute D.O.S. l5 2 0.771

Calcium l2-cyanocthuxy steuratc D.O.S. l5 1 0.680

Barium 9( IOLcyanoethoxy stearutc D.O.S. l5 1 0.775

Aluminum 9( l0j-cyanoethoxy stearate D.O.S. 7 0 0.803

Lithium 9( l0)-cyanoethoxy stearate DIOA l5 3 0.685

Lithium Stearate DlOA l5 3 0.816

Lithium 9( IOJ-cyanoethoxy stearate D.O.A. l5 3 0.820

Lithium Stearate D.O.A. l5 3 0.898

Lithium 9( l0)-cyanoethoxy stearate DPDP l5 4 0.798

Lithium Stearate DPDP l5 3 0.786

We claim:

1. A difunctional fatty soap of the general formula 14. Aluminum 9( l0)-cyanoethoxystearate. 

1. A DIFUNCTIONAL FATTY SOAP OF THE GENERAL FORMULA
 2. The difunctional fatty soap of claim 1 wherein the sum of x and y is
 15. 3. The difunctional fatty soap of claim 2 wherein R is lithium.
 4. The difunctional fatty soap of claim 2 wherein R is sodium.
 5. The difunctional fatty soap of claim 2 wherein R is calcium.
 6. The difunctional fatty soap of claim 2 wherein R is barium.
 7. The difunctional fatty soap of claim 2 wherein R is aluminum.
 8. Lithium 9(10)-cyanoethoxy stearate.
 9. Lithium 12-cyanoethoxy stearate.
 10. Sodium 9(10)-cyanoethoxy stearate.
 11. Sodium 12-cyanoethoxy stearate.
 12. Calcium 12-cyanoethoxy stearate.
 13. Barium 9(10)-cyanoethoxystearate.
 14. Aluminum 9(10)-cyanoethoxystearate. 